The focus of the first copy of this lens I had had severe focussing problems (front focus), I brought it back and the copy I have now has less front-focussing, but still enough to notice at smaller apertures. I compared it to my kit lens (18-55mm f3.5-5.6) at the same focal lengths and apertures, and the kit lens focusses correctly. So I'm sending this lens back as well, I hope my third one will work correctly...